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Auteur Rabearisoa, N.; Sabarros, P. S.; Romanov, E. V.; Lucas, V.; Bach, P. url  doi
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  Titre Toothed whale and shark depredation indicators: A case study from the Reunion Island and Seychelles pelagic longline fisheries Type Article scientifique
  Année (down) 2018 Publication Revue Abrégée PLOS ONE  
  Volume 13 Numéro 8 Pages e0202037  
  Mots-Clés Indian Ocean; Seychelles; Sharks; Tuna; Fisheries; Economics; Killer whales; Whales  
  Résumé Depredation in marine ecosystems is defined as the damage or removal of fish or bait from fishing gear by predators. Depredation raises concerns about the conservation of species involved, fisheries yield and profitability, and reference points based on stock assessment of depredated species. Therefore, the development of accurate indicators to assess the impact of depredation is needed. Both the Reunion Island and the Seychelles archipelago pelagic longline fisheries targeting swordfish (Xiphias gladius) and tuna (Thunnus spp.) are affected by depredation from toothed whales and pelagic sharks. In this study, we used fishery data collected between 2004 and 2015 to propose depredation indicators and to assess depredation levels in both fisheries. For both fisheries, the interaction rate (depredation occurrence) was significantly higher for shark compared to toothed whale depredation. However, when depredation occurred, toothed whale depredation impact was significantly higher than shark depredation impact, with higher depredation per unit effort (number of fish depredated per 1000 hooks) and damage rate (proportion of fish depredated per depredated set). The gross depredation rate in the Seychelles was 18.3%. A slight increase of the gross depredation rate was observed for the Reunion Island longline fleet from 2011 (4.1% in 2007–2010 and 4.4% in 2011–2015). Economic losses due to depredation were estimated by using these indicators and published official statistics. A loss of 0.09 EUR/hook due to depredation was estimated for the Reunion Island longline fleet, and 0.86 EUR/hook for the Seychelles. These results suggest a southward decreasing toothed whale and shark depredation gradient in the southwest Indian Ocean. Seychelles depredation levels are among the highest observed in the world revealing this area as a “hotspot” of interaction between pelagic longline fisheries and toothed whales. This study also highlights the need for a set of depredation indicators to allow for a global comparison of depredation rates among various fishing grounds worldwide.  
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  Volume de collection Numéro de collection Edition  
  ISSN 1932-6203 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2401  
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Auteur Nikolic, N.; Lauretta, M.; Patucca, A.; Morandeau, G. doi  openurl
  Titre Characterization and standardization of the Atlantic albacore French pelagic trawl fishery Type Article scientifique
  Année (down) 2018 Publication Revue Abrégée Aquat. Living Resour.  
  Volume 31 Numéro Pages 31  
  Mots-Clés Albacore; Atlantic; behavior; catch; catch rates; fisheries; habitat; migration; north pacific albacore; ocean; stock; thunnus-alalunga; trawl; tuna  
  Résumé We compiled and analysed logbook data from the French trawl albacore fishery covering the period 1991-2015. The dataset comprised catch and effort data for the French fleet operating in the Bay of Biscay and Celtic Sea, as well as spatiotemporal and gear characteristics. Generalized linear modelling was used to model spatial, seasonal, environmental, and gear covariates of fleet CPUE rates. A long-term index of relative abundance is provided that can be integrated into the stock assessment of North Atlantic albacore. The analysis revealed higher albacore CPUE associated with relatively low sea surface temperature and distinct seasonal effects. The derived abundance trend for the French trawl fishery agreed with the estimated time series of stock abundance from recent assessments.  
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  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0990-7440 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2426  
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Auteur Pecoraro, C.; Babbucci, M.; Franch, R.; Rico, C.; Papetti, C.; Chassot, E.; Bodin, N.; Cariani, A.; Bargelloni, L.; Tinti, F. doi  openurl
  Titre The population genomics of yellowfin tuna (Thunnus albacares) at global geographic scale challenges current stock delineation Type Article scientifique
  Année (down) 2018 Publication Revue Abrégée Sci Rep  
  Volume 8 Numéro Pages 13890  
  Mots-Clés archival tag data; atlantic bluefin tuna; connectivity; conservation; divergence; fisheries management; habitat utilization; loci; pacific-ocean; relatedness  
  Résumé Yellowfin tuna, Thunnus albacares, is one of the most important seafood commodities in the world. Despite its great biological and economic importance, conflicting evidence arises from classical genetic and tagging studies concerning the yellowfin tuna population structure at local and global oceanic scales. Access to more powerful and cost effective genetic tools would represent the first step towards resolving the population structure of yellowfin tuna across its distribution range. Using a panel of 939 neutral Single Nucleotide Polymorphisms (SNPs), and the most comprehensive data set of yellowfin samples available so far, we found genetic differentiation among the Atlantic, Indian and Pacific oceans. The genetic stock structure analysis carried out with 33 outlier SNPs, putatively under selection, identified discrete populations within the Pacific Ocean and, for the first time, also within the Atlantic Ocean. Stock assessment approaches that consider genetic differences at neutral and adaptive genomic loci should be routinely implemented to check the status of the yellowfin tuna, prevent illegal trade, and develop more sustainable management measures.  
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  Langue English Langue du Résumé Titre Original  
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  Volume de collection Numéro de collection Edition  
  ISSN 2045-2322 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2437  
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Auteur Torres-Irineo, E.; Dreyfus-Leon, M.; Gaertner, D.; Salas, S.; Marchal, P. doi  openurl
  Titre Adaptive responses of tropical tuna purse-seiners under temporal regulations Type Article scientifique
  Année (down) 2017 Publication Revue Abrégée Ambio  
  Volume 46 Numéro 1 Pages 88-97  
  Mots-Clés atlantic; behavior; Closed season; eastern pacific-ocean; eastern tropical pacific; Fisher behaviour; Fisheries management; fishing strategies; fleet dynamics; mixed fisheries; model; Purse-seine fishing; state; trawlers; Tropical tuna  
  Résumé The failure to achieve fisheries management objectives has been broadly discussed in international meetings. Measuring the effects of fishery regulations is difficult due to the lack of detailed information. The yellowfin tuna fishery in the eastern Pacific Ocean offers an opportunity to evaluate the fishers' responses to temporal regulations. We used data from observers on-board Mexican purse-seine fleet, which is the main fleet fishing on dolphin-associated tuna schools. In 2002, the Inter-American Tropical Tuna Commission implemented a closed season to reduce fishing effort for this fishery. For the period 1992-2008, we analysed three fishery indicators using generalized estimating equations to evaluate the fishers' response to the closure. We found that purse-seiners decreased their time spent in port, increased their fishing sets, and maintained their proportion of successful fishing sets. Our results highlight the relevance of accounting for the fisher behaviour to understand fisheries dynamics when establishing management regulations.  
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  Langue English Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 0044-7447 ISBN Médium  
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  Numéro d'Appel MARBEC @ alain.herve @ collection 2072  
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Auteur Pons, M.; Branch, T.A.; Melnychuk, M.C.; Jensen, O.P.; Brodziak, J.; Fromentin, J.M.; Harley, S.J.; Haynie, A.C.; Kell, L.T.; Maunder, M.N.; Parma, A.M.; Restrepo, V.R.; Sharma, R.; Ahrens, R.; Hilborn, R. url  doi
openurl 
  Titre Effects of biological, economic and management factors on tuna and billfish stock status Type Article scientifique
  Année (down) 2017 Publication Revue Abrégée Fish Fish  
  Volume 18 Numéro 1 Pages 1-21  
  Mots-Clés Fisheries management; marine conservation; stock assessment; stock status; Tuna fisheries  
  Résumé Commercial tunas and billfishes (swordfish, marlins and sailfish) provide considerable catches and income in both developed and developing countries. These stocks vary in status from lightly exploited to rebuilding to severely depleted. Previous studies suggested that this variability could result from differences in life-history characteristics and economic incentives, but differences in exploitation histories and management measures also have a strong effect on current stock status. Although the status (biomass and fishing mortality rate) of major tuna and billfish stocks is well documented, the effect of these diverse factors on current stock status and the effect of management measures in rebuilding stocks have not been analysed at the global level. Here, we show that, particularly for tunas, stocks were more depleted if they had high commercial value, were long-lived species, had small pre-fishing biomass and were subject to intense fishing pressure for a long time. In addition, implementing and enforcing total allowable catches (TACs) had the strongest positive influence on rebuilding overfished tuna and billfish stocks. Other control rules such as minimum size regulations or seasonal closures were also important in reducing fishing pressure, but stocks under TAC implementations showed the fastest increase of biomass. Lessons learned from this study can be applied in managing large industrial fisheries around the world. In particular, tuna regional fisheries management organizations should consider the relative effectiveness of management measures observed in this study for rebuilding depleted large pelagic stocks.  
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  Langue en Langue du Résumé Titre Original  
  Éditeur de collection Titre de collection Titre de collection Abrégé  
  Volume de collection Numéro de collection Edition  
  ISSN 1467-2979 ISBN Médium  
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  Numéro d'Appel MARBEC @ isabelle.vidal-ayouba @ collection 2079  
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